1. Field of the Invention
The present invention relates to a thin-film magnetic head that comprises a closure and makes contact with a magnetic recording medium, a head gimbal assembly (HGA) with the thin-film magnetic head and a magnetic recording apparatus with the HGA and the medium.
2. Description of the Related Art
A magnetic disk drive apparatus such as a hard disk drive (HDD) or a flexible disk drive (FDD) is a representative example of the magnetic recording apparatuses, which is portable and lower in price per byte than semiconductor memory. Recently, because the volume of various data becomes larger due to the spread use of the multimedia and the Internet, the magnetic disk drive apparatus is strongly required to have much larger capacity and to be further miniaturized.
In the situation, a contact-type apparatus is worth noting because of its possibility of higher recording density, which, for example, has a loading mechanism for transferring an inserted cartridge including a disk to the predetermined position, a rotary drive mechanism for holding and rotating the disk in the transferred cartridge, a magnetic head device for writing data signals to the rotated disk and reading data signals from it, and a moving mechanism for moving the magnetic head device in the radial direction on the disk.
The magnetic head in the magnetic head device writes and reads data signals in contact with the magnetic disk. A Metal-In-Gap (MIG) head has conventionally used as the contact-type head. However, in order to respond the increasing data storage capacity and the further miniaturization of the magnetic disk drive apparatus, a thin-film magnetic head for an HDD, which inherently meets higher recording density, is being applied to the contact-type apparatus. The thin-film magnetic head for the HDD has a structure suitable for flying on the magnetic disk without contact during read and write operations. Therefore, the simple use of the thin-film magnetic head under the contact condition may cause a significant wear or crash of the head. To avoid the problem, U.S. Pat. No. 6,947,259 proposes the limitation to a predetermined range of the distance between an electromagnetic transducer (magnetic head element) and the contact edge of an overcoat layer. Further, Japanese Patent Publication No. 06-309625A describes a contact-type head for perpendicular magnetic recording with the sliding surface of an antiwear layer.
Furthermore, U.S. Pat. No. 5,142,768 and Japanese Patent Publications Nos. 08-321012A and 06-012622A describe a magnetic head used for a magnetic tape drive etc., which has a bonded protection plate such as a closure block.
However, in the head described in U.S. Pat. No. 6,947,259, the sliding surface of the protective film is still worn largely, and especially when an alumina thick film is used as the protective film, the degree of wear becomes larger than that of the slider substrate. Further, the formation of the thick film with thickness of 50 to 200 micrometers requires significant man-hours. A contact-type head described in Japanese Patent Publication No. 06-309625A has the same kind of problem.
Further, when the “closure-type” magnetic head described in U.S. Pat. No. 5,142,768 and Japanese Patent Publications Nos. 08-321012A and 06-012622A is used for a magnetic disk drive apparatus such as a FDD, the contact edge of the whole magnetic head is rather separated from the contact end of the head element during read and write operations. Therefore, the area of the magnetic disk such as the flexible disk opposed to the end of the head element is bent, then the bending is likely to cause the distance between the end of the head element and the disk surface to be fluctuated. As a result, read and write performances may become unstable.